1. PressureGuard
Module One - Introduction

2. Contents SCH Actuator Design Philosophy Key Features
Control System - Standard Components
Standard Control Components
Components Overview
Reservoir
Handpump
HP Gauge
Pressure Regulator
LP Accumulator
Manual Reset Valve
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3. Contents Control System - Shutdown Components Shutdown Devices
Pressurematic Pilot
SP Pressure Pilot
Pilot Accessories
Control System - Operation
Manual Operation / Arming
Actuator Supply Regulation
Remote Arming
Remote Shutdown
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4. SCH Actuator Design Philosophy
Self-Contained Hydraulic (SCH) actuators are most commonly used for applications in which automatic valve control is required but there is no external power source available to power the actuator.
The most common specific application is for ensuring valve shutdown on wellheads where an actuator power source is either unreliable or non existent.
The basic design philosophy for a SCH actuator is that a hydraulic handpump is used to pump hydraulic fluid under pressure into an actuator’s hydraulic cylinder which is used to compress the actuator’s spring as well as to move the mainline valve to its normal operating position.
In the event of a situation in which automatic valve operation is required, a control component is used to vent the hydraulic fluid from the actuator’s cylinder which allows the compressed spring to move the valve to its fail-safe position.
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5. Key Features
Suitable for remote, unmanned, unpowered and critical service
Adaptable to either quarter-turn or linear operated valves
Field-proven in extreme climatic conditions
Standard hydraulic model for all valve sizes and configurations
Eliminates requirement for plant air, fuel gas, electricity or expensive nitrogen backup systems
Modular design to simply maintenance
High Pressure, zero leakage control
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6. Control System - Standard Components
All SCH actuator control systems are supplied with a basic manifolded control system which provides one-way local control via the handpump.
In addition to reliable and leak free mainline valve automation, the manifold based control system enables quick and simple maintenance.
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7. Control System - Components Overview
The standard SCH control system shown below is supplied as standard with the following control components:
LP Pressure Gauge
HP Pressure Gauge
HP Relief
Valve
Handpump
Assembly
Pressure
Regulator
Reservoir
Actuator
LP Relief
Valve
LP Accumulator
Manual Reset Valve
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8. Control Components - Reservoir
Contains hydraulic fluid for actuator and controls.
Reservoir is non-pressurized (closed loop option available)
Houses both HP and LP relief valves
Fitted with hydraulic level indicator
Fitted with drain plug
Fitted with suction screen
Simple to remove for inspection and maintenance of internal components
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9. Control Components - Handpump
Used to pressurize the hydraulic fluid, thereby compressing the actuator’s spring and moving the mainline valve to it’s normal operating position.
Positive displacement
Weatherproof boot
Chrome plated ram
Replaceable discharge filter and check valve
Anodized aluminum handpump handle
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10. Control Components - HP Gauge
Monitors the hydraulic pressure in the high pressure line which also indicates the supply pressure available to the actuator.
Stainless steel body
Liquid filled
Brass Bordon tube
Fitted with snubber
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11. Control Components - Pressure Regulator
Used to reduce to the hydraulic pressure in the high pressure actuator supply circuit (typically 1,000 to 1,200 psig) to a low pressure (typically 100 psig) allowing low pressure control components in the control circuit to be used downstream of the regulator.
ENP brass body
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12. Control Components - LP Gauge
Monitors hydraulic pressure in the low pressure control circuit.
Stainless steel body
Liquid filled
Brass Bordon tube
Fitted with snubber
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13. Control Components - LP Accumulator
Prevents cyclic transfer, due to temperature changes, of hydraulic fluid from the high pressure actuator supply circuit to the low pressure control circuit and thereby prevents temperature induced creep of the actuator.
Eliminates temperature induced actuator movement for -46°C to 77°C ambient temperature environments
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14. Control Components - Manual Reset Valve
Used to provide a local manual reset facility following mainline valve shutdown.
High flow rates to provide fast mainline valve shutdown
Normally closed, manual reset, pilot operated relay
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15. Control Components - Shutdown Devices
The standard SCH control system always requires at least one additional control component to initiate valve shutdown. This type of component is used to initiate the depressurization of the system allowing the spring in the actuator to move the mainline valve to its failed position.
Most common of these shutdown devices are pressure pilot valves, solenoid valves and manual ball valves.
Manual Reset
The picture shows a Pressurematic Pilot fitted with a manual reset valve (P-MR type) being used as the shutdown device.
Pressurematic
Pilot
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16. Control Components - Pressurematic Pilot
All Pressurematic pilot valves provide high and low pipeline pressure sensing on gas or liquid pipelines and can be fitted with either an automatic or manual reset facility.
P-AR Pressurematic Pilot
(Automatic Reset)
P-MR Pressurematic Pilot
(Manual Reset)
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17. Control Components - SP Pressure Pilot
SP Pressure Pilot valves provide either high or low pipeline pressure sensing on gas or liquid pipelines and can be fitted with either an automatic or manual reset facility.
SP Pressure Pilot for sensing low (falling) pipeline pressure
SP Pressure Pilot for sensing high (rising) pipeline pressure
SP Pressure Pilot for sensing high (rising) pipeline pressure c/w manual reset valve
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18. Control Components - Pilot Accessories
In addition to pilot valves, Bettis Canada manufacture both ISO Test Valves and Flow Tees to assist with installation and calibration. Both components are available in a range of materials and trims to cover all types of pipeline media.
ISO Test Valve
Flow Tees
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19. Operation - Manual Operation / Arming
The HP Pressure Gauge measures the fluid pressure in
the HP Actuator Circuit and therefore the pressure being
supplied to the actuator from the handpump. 2
During manual arming of the system, both the shutdown control component
(shown here as a solenoid valve) and the Manual Reset Valve in the LP
Control Circuit are in the closed position; continued operation of the handpump
will pressurize the circuit until the LP Pressure Regulator’s set-point is reached.
The HP Relief Valve limits the maximum pressure (typically 1200 psig)
that can be generated by the handpump in the HP Actuator Circuit.
The LP Accumulator prevents cyclic transfer, due to temperature
changes, of hydraulic fluid from the high pressure actuator supply
circuit to the low pressure control circuit and thereby prevents
temperature induced creep of the actuator.
The LP Pressure Gauge measures the
fluid pressure in the LP Control Circuit.
Raising the handpump handle sucks fluid from the
reservoir though an integral check valve. On the
down-stroke the fluid is forced under pressure
through a filter and another check valve into the
HP Actuator Circuit (shown in red).
The LP Relief Valve prevents potential over-pressurization in the
LP Control Circuit which could be caused by thermal fluid expansion. 1
The Manual Reset Valve is
armed by pulling its toggle
to the manual position.
The LP Pressure Regulator limits the maximum pressure that is supplied
(typically 100 psig) to the LP Control Circuit (shown in green).
When the LP Control Circuit has been fully pressurized to the
LP Pressure Regulator’s set-point no more fluid can pass
though the regulator. Continued handpump operation forces
more fluid into the HP Actuator Circuit thereby increasing
the pressure in the circuit. The increasing pressure
pressurizes the actuator’s hydraulic cylinder thereby
compressing its spring and stroking the mainline valve to
its normal (here shown as open) operating position.
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20. Operation - Actuator Supply Regulation
When the pressure in the HP
Actuator Circuit reaches the
set-point of the HP Relief
Valve it will open, releasing fluid
back to the Reservoir until the
pressure falls below its set-
point. Continued operation
of the handpump will simply
cause the HP Relief Valve to
continue to vent fluid back to
the reservoir.
Continued operation of the handpump after the actuator
has stroked the mainline valve to its normal operating
position (shown here as open) will increase the pressure
in the HP Actuator Circuit.
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21. Operation - Remote Arming1
Once the shutdown device is in the open position,
it allows a pilot signal to travel to the Manual
Reset Valve. When the Manual Reset Valve
senses the pilot signal, its spool moves slightly
allowing the toggle to move to the remotely
armed position. Once the Manual Reset
Valve is in the remotely armed position,
loss of the pilot signal to it will result in
mainline valve shutdown.
To initiate remote arming of the system, the Manual
Reset Valve has to be manually armed and the
system pressurized via the handpump. After the
system has been pressurized, the shutdown device
(here shown as a solenoid valve) has to be in the
open position (its normal operating position).
Here the solenoid valve has been energized
to move it to the open position.
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22. Operation - Remote Shutdown
As the LP Control Circuit begins to depressurize, the LP
Pressure Regulator senses the pressure drop and
attempts to maintain the pressure in the circuit by allowing
fluid to pass though it from the HP Actuator Circuit. Due
the loss of fluid though the LP Pressure Regulator from
the HP Actuator Circuit, it begins to depressurize.
During a failure condition, the shutdown control component
will move to the closed position (here, the solenoid valve has
been de-energized). In the closed position, the shutdown device
allows the fluid in the Manual Reset Valve pilot line to be vented
back to the reservoir, thereby depressurizing the line and
allowing the Manual Reset Valve to move to the open position.
Following the mainline valve shutdown, all fluid is returned back
to the reservoir and both the HP Actuator and LP Control
circuits become fully depressurized.
As the HP Actuator Circuit depressurizes and the pressure
from the actuator’s hydraulic cylinder is removed, the spring
causes the mainline valve to be stroked to its failed position
(here shown as closed).
In the open position, the Manual
Reset Valve allows fluid from
the LP Control Circuit to be
vented back to the reservoir.
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23. End of Module One
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